FR2598715A1 - BITUMINOUS EMULSION ADDED WITH A POLYMER AND METHOD FOR REDUCING THE TIME OF TAKING THE EMULSION - Google Patents

Abstract

THE INVENTION RELATES TO CATIONIC EMULSIONS OF ASPHALT, BITUMEN, COAL TAR OR THEIR MIXTURE. THE SETUP TIME OF CATIONIC EMULSIONS OF ASPHALT, BITUMEN, COAL TAR OR THEIR MIXTURE MAY BE SHORTENED BY INCORPORATING SUCH AN EMULSION OF AT LEAST 0.001 PART BY WEIGHT, PER 100 PARTS BY WEIGHT ON A DRY BASIS OF THE SAID EMULSION OF A POLYCARBOXYLIC ACID. APPLICATION TO ROAD COATINGS AND SIMILAR COATINGS.

Description

The present invention relates to the modification of cationic emulsions

  asphalt, bitumen, coal tar or their mixture. The term asphalt used in this specification covers natural asphalts such as Trinidad Lake asphalts and synthetic asphalts produced by refining crude oil.

  Emulsions of asphalt, bitumen and coal tar have many applications, including, but not limited to, the production of an aggregate coating. One of the problems with bitumen emulsions is the time taken by the emulsion to start setting and the time it takes to dry. This is extremely expensive when traffic has to be interrupted.

  for a long time on a highway lane.

  The properties of asphalt, bitumen, coal tar or their mixture can be improved by the incorporation of a polymer. This improves adhesion, ductility, tensile strength and

  the low temperature properties of asphalt, bitumen or coal tar. This can be achieved by melting the asphalt and adding the polymer.

  This process spends energy. The addition of polymer to asphalt, bitumen, coal tar or

  their mixing can be carried out by mixing emulsions of this material with a latex of the polymer. Although this process spends less energy, it further enhances the setting times and drying times of bituminous emulsions.

  One approach for improving the drying time of bituminous emulsions has been to include in the composition a gelling agent of the type of a silicofluoride. Examples of this approach include CA 96: 163961k of European Patent No. 45,619 issued Feb. 10, 1982 to British Petroleum Co. Ltd .; CA 83: 196173g of Belgian Patent No. 821,210 published February 17, 1975 in the name of Kamenouhelve Poly Oborove Rzeditelstvi; and CA 81: 171549n of the Patent Application of the Federal Republic of Germany DEOS N 2 363 085 published July 4, 1974 in the name of Rambelli Giacinto. Silicofluorides are gelling agents that depend on time. As a result, the silicofluoride is mixed with the emulsion shortly before it is taken. This requires a two-component application system or the use of the system immediately after the addition of the gelling agent. Silicofluorides are used as agents

  gelling agents with anionic emulsions.

  One approach is to add one or more thickeners to bituminous emulsions.

  This approach is taught in U.S. Patent No. 4,492,781 which discloses a composition formed of an asphalt / rubber / acrylic copolymer emulsion (100-10: 0-90: 0-70), a polymer water-soluble component, a reinforcing component, an aggregate, a crosslinking and thickening agent and a resin ester. The acrylic polymer described in the latter patent is a copolymer of ethylene and acrylic acid. The water-soluble polymer referred to as RETEN is an acrylamide copolymer. None of these types of polymers are

  the C 3 or C 4 ethylenically unsaturated carboxylic acid polymer required by the present invention.

  In addition, these types of polymers do not improve the setting or drying time of asphalt, bitumen or coal tar emulsions which have been modified.

  with an aqueous emulsion of a polymer.

  None of the documents of the prior art teaches that a cationic emulsion of asphalt, bitumen, coal tar or their mixture may, in admixture with an aggregate, set and dry more rapidly because of incorporation of relatively small amounts of acrylic acid polymers

  or methacrylic low molecular weight.

  The term "plug" as used herein refers to the stage at which an aggregate on contact

  an aqueous emulsion of bitumen, asphalt, tar or their mixture begins to resist movement.

  The setting time means the time it takes for an emulsion of asphalt, bitumen, tar or its mixture to harden from its initial contact with an aggregate. The present invention provides a method for reducing the setting time. a cationic emulsion of bitumen, asphalt, coal tar or a mixture thereof, which process comprises incorporating into said emulsion an effective amount of a solution of a cationic emulsifier and a sufficient amount of a polymer selected from the group of polymers of acrylic acid, methacrylic acid, their mixture or their salts to form a workable emulsion

  which hardens in less than about 40 minutes.

  The polymer is preferably used in an amount sufficient to have at least about 0.001 part by dry weight of said acrylic acid, methacrylic acid polymer or mixture thereof or salts thereof per 100 parts by weight. on a dry basis of said cationic bituminous emulsion. The present invention also provides a composition comprising: 100 parts by weight on a dry basis of a cationic emulsion selected from the group consisting of asphalt, bitumen, coal tar and mixtures thereof; and at least about 0.001 parts by weight, on a dry basis, of a polymer selected from the group consisting of

  a polymer of acrylic acid, methacrylic acid, their mixtures or their salts.

  Cationic emulsions of asphalt, bitumen, coal tar or their mixture may be purchased commercially or prepared in a high shear colloid mill. The actual preparation of these emulsions is not a part of the present invention.

  The setting time should be less than about 40 minutes and preferably less than 30 minutes. If the cationic emulsion of asphalt, bitumen, coal tar or their mixture is not modified with a latex, the set time may be reduced to 5 minutes. If the emulsion is modified with a latex of a polymer, the setting time can range from about 15 to 40 minutes.

  According to the present invention, these cationic emulsions of asphalt, bitumen, coal tar and their mixture are modified with at least about 0.001, preferably up to about 1, preferably from 0.001 to 0.5 parts by weight. on a dry basis of a polymer selected from the group of polymers of acrylic acid, methacrylic acid, their mixtures or their salts.

  The solutions of these polymers are anionic. Cationic solutions of these polymers can be prepared using standard techniques known in the industry. A cationic emulsifier is added to the anionic solution of the polycarboxylic acid salt, and then the pH is adjusted to a value of from about 1 to about 5, more preferably from about 2 to about 4, preferably about 3 to 3. 5. The pH of the solution is adjusted with an acid. Useful inorganic acids include hydrochloric acid, sulfuric acid and phosphoric acid. Useful organic acids

25 30 35

  include lower alkyl acids (C1 to C4) such as acetic acid, formic acid and oxalic acid. The surfactant contains a nitrogen, sulfur or phosphorus atom. The surfactants may be onium compounds. Surfactants containing a nitrogen atom may be a primary, secondary or tertiary amine. A particularly useful class of surfactants includes tertiary amines of the formula R - N (CH 2 -CH 2 -O) y H wherein R is C 10 -C 18 alkenyl and

  x and y are integers whose sum has a value of 2 to 20.

  Other surfactants include amphoteric surfactants that contain both a carboxyl group and a nitrogen atom, including ampholytes and betaines. The surfactant may be an amide oxide. In general, the surfactant is used in an amount of up to about 10% by weight of the total polymer added to the cationic emulsion. The surfactant is advantageously used in an amount of about 5 to 10% by weight based on the total weight added to the cationic emulsion of asphalt, bitumen, coal tar or their mixture.

  The acrylic or methacrylic acid polymer or mixtures thereof or salts thereof is advantageously mixed with a latex of a polymer selected from the following group: Polymers comprising about 20 to 60, preferably 20 to 40% by weight of a C8-C12 vinyl aromatic monomer which may not be substituted or substituted by a C1-C4 alkyl radical or a chlorine or bromine atom; and about 80 to 1, preferably 80 to 60% by weight of a C to C6 conjugated diolefin. SBR polymers are representative of this class. The SBR is advantageously a latex prepared by a cold emulsion polymerization process. Suitable vinyl aromatic monomers, in addition to styrene, include alphamethylstyrene, tert-butylstyrene, chlorostyrene and bromostyrene. Suitable conjugated diolefins, in addition to 1,3-butadiene, include isoprene. The above polymers may contain one or more functional monomers such as carboxylic acids, aldehydes, esters, amides or their copolymerizable mixture. The functional monomer (s) may be present in an amount of from about 0.5 to about 10% by weight. Suitable monomeric carboxylic acids are C 3 to C 6 ethylenically unsaturated carboxylic acids including acrylic acid, methacrylic acid, fumaric acid and itaconic acid. The functional monoamine may be a C3-C6 ethylenically unsaturated aldehyde such as acrolein. The functional monomer may be a C1 to C4 alkyl or hydroxyalkyl ester of a C3 to C6 ethylenically unsaturated carboxylic acid. Suitable monomeric esters include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, hydroxyl acrylate and hemihydroxyethyl acrylate. esters of dicarboxylic acids such as the ethyl half-ester of itaconic acid and the hydroxyethyl half-ester of maleic acid. The functional monomer may be an amide of a C to C carboxylic acid such as acrylamide or methacrylamide. The amides may not be substituted or may be substituted on the nitrogen atom by an alkyl radical or a radical

  C1-C4 hydroxyalkyl. Suitable substituted amides include N-methylacrylamide, N-ethylacrylamide, N-methylolacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-methylolmethacrylamide.

  The polymer may comprise one or more C4 to C6 conjugated diolefin monomers which may

  not be substituted or substituted by a chlorine atom. Preferred representatives of this group are natural rubber or chloroprene latices.

  The polymer may be a nitrilic polymer.

  These polymers include, for example, up to% by weight of a C3 to C6 alkenylnitrile, the remainder being a C4 to C6 conjugated diolefin. A preferred nitrile is acrylonitrile and preferred diolefins are butadiene and isoprene. These polymers are particularly useful when the final composite may be exposed to oils or solvents. This type of asphalt, bitumen or coal tar emulsion is particularly useful in the construction of refueling areas at airports. The polymer may be a copolymer of from 75% by weight of a C 2 or C 3 olefin and from 10 to 25% by weight of a C 3 or C 4 ethylenically unsaturated carboxylic acid. The preferred monomers are

  ethylene and acrylic or methacrylic acid.

  The polymer may be a polymer of a C 2 or C 3 alpha-olefin and an unsaturated ester of a saturated organic acid. These polymers may optionally contain up to 10, preferably about 0.5 to 10,% by weight of a functional monomer. Such

  monomers have been commented on above.

  These polymers comprise, for example: 1, 1 1 about 1 to 40, preferably about 5 to 25% by weight of an alpha-olefinic monomer C or C3, about 99 to 50, preferably 95 to% by weight of a C2 to C8 alkenyl or hydroxyalkenyl ester of a C1 to C12 saturated carboxylic acid; and optionally, about 0.5 to 10, preferably about 0.5 to 5, weight percent of one or more monomers selected from the group consisting of: C3-C6 ethylenically unsaturated carboxylic acids; C3 to C6 ethylenically unsaturated aldehydes; C1-C4 alkyl and hydroxyalkyl esters of a C3-C6 ethylenically unsaturated carboxylic acid; and amides of C 3 to C 6 ethylenically unsaturated carboxylic acids, which amides may not be substituted or may be substituted on

  the nitrogen atom with up to two radicals selected from C1 to C4 alkyl radicals and C1 to C4 hydroxyalkyl radicals.

  Suitable alpha-olefins and functional monomers have been discussed above. of the

  C2-C8 alkenyl or hydroxyalkenyl esters of suitable C1-C12 saturated carboxylic acids include vinyl esters such as vinyl acetate and homologues thereof; and allyl esters such as allyl acetate and its counterparts.

  The solution of the acrylic acid, methacrylic acid polymer or mixture thereof is normally added to the latex in an amount of about 0.1 to about 2.0, more preferably 0.1 to 1.0, especially from 0.1 to 0.5 parts by weight on a dry basis for parts by weight on a dry basis of polymer forming the latex. After the addition of the cationic emulsifier, the latex is made cationic by pH adjustment

with an inorganic acid.

  Polymers of acrylic acid, methacrylic acid, mixtures thereof or salts thereof which are preferred are soluble in water. These polymers advantageously have a molecular weight of less than 100,000 and preferably less than 60,000. These molecular weight limits are practical limits.

  from the point of view of viscosity problems which arise when mixing high molecular weight acrylic acid or methacrylic acid polymer salts with an anionic latex before rendering the latter cationic.

  The cationic latex mixture is then added to the cationic emulsion of asphalt, bitumen or coal tar. The latex is added in an amount of up to about 20 parts by weight of said dry base polymer. Preferably, the polymers are used in an amount of up to about 20, preferably about 3 to

  parts by weight on a dry basis per 100 parts by weight on a dry basis of asphalt, bitumen, coal tar or mixture thereof.

  These emulsions are normally applied to a surface, and then about 1000 parts by weight of aggregate are spread over about 100 parts by weight on a dry basis of asphalt, bitumen or tar. The aggregate may be a mixture of a fine aggregate such

  sand and a coarser aggregate such as gravel. In some applications, for example to seal a surface, the aggregate may be entirely formed of fine aggregate such as sand.

15 20 25 30 35

  The following examples are intended to illustrate the invention and should in no way limit its scope. In the examples which follow, unless otherwise specified, the parts are parts by weight on a dry basis.

  In the tests indicated below, a cationic bituminous emulsion obtained under the trade name "Actimul RE 65 X" was used from the Society for Road Chemistry (SCR).

  The effect of a polyacrylic acid salt on setting time and the drying time of the bituminous emulsion is demonstrated by the following experiment.

  A sample of a low molecular weight polyacrylic acid salt sold under the trade name "Dispex N40" was made cationic by the addition of about 7 parts per 100 parts of polymer of a tertiary amine sold. under the trademark "Noramox S11" and adjusting the pH to 3 to 3.5 with hydrochloric acid. A sufficient amount of this cationic polyacrylic acid was added to the cationic bituminous emulsion to provide 0.3 parts by weight of polyacrylic acid per 100 parts by weight of dry basis bitumen. The bituminous emulsion was then spread on a polyester cup and gravelled with a washed and dried aggregate of 6 to 10 mm particles. The time after which the chippings could no longer be moved and the time after which the emulsion had dried was noted.

  Bituminous emulsion Bituminous emulsion Polyacrylic acid Start of setting Final drying min 0.3 min fully gelled after 10 min min 1 1 This experiment clearly shows that cationic bitumen emulsion reduction is reduced by the addition of 0.3 part by weight of a low molecular weight polyacrylic acid per 100 parts by weight of bitumen on a dry basis. A series of various latexes has been modified with varying amounts of a molecular weight polyacrylic acid sodium salt. The modified latex was then made cationic by the addition of 7 parts per 100 parts of polymer of a tertiary amine sold under the trade name "Noramox S-11". The pH of the latex was adjusted to 3-3.5 with hydrochloric acid. Then, 3 parts by weight on a dry basis of the resulting cationic latex were added to 100 parts by weight on a dry basis of the bituminous emulsion. The setting time and the drying time of the bituminous emulsion were determined as described above. The results are reproduced on

Table II.

z 1.

Latex

TABLE If

  Poly-acrylic acid salt taken, min Drying time, min Asphalt (unmodified) SBR at 23% styrene

120

more than 240; you

0.1 0.25 0.5 0.3

180

150

80

120

  SBR at 23% styrene reinforced with 6 parts, per 100 parts of rubber, of high styrene content resin 30

40 45

0.4 0.5

30 30

  more than 240 150 135 Latex "POLYSAR" 3720 SBR carboxylated Latex "POLYSAR" 3515 SBR carboxylated Latex "POLYSAR" 3703 SBR carboxylated "BAYPRENE" Latex polychloroprene "KA 8306" Natural latex 0.3 over 30 240

135

more than 50,240

180

0.3

240

0.3 100 240 0.3

180

more than

80

  0.3 "POLYSAR" is a trademark of Polysar Limited

  "BAYPRENE" is a trademark of BAYER AG.

  The experiment carried out with the SBR latex containing 23% styrene was repeated except that 0.3 part of polyacrylic acid was replaced by 0.3 part of acrylonitrile acrylic acid copolymer. The start time was greater than 90 minutes. The drying time was greater than 240 minutes.

  A series of modified cationic asphalt emulsions, prepared as above, were subjected to a cohesive strength study in accordance with the Global Vialit Plate Adhesive Test of the Central Bridges and Roads Laboratory ( sometimes called French

Chip Test).

  In this test, two 200 mm / 200 mm / 3 mm stainless steel plates are coated with latex modified bitumen emulsion (EBM emulsion) at a dry basis weight of 1.5 kg / m 2. 12 mm diameter stainless steel balls are placed in the EBM emulsion and the plates are dried for 24 hours at room temperature. Then, one of the plates is allowed to dry for a further 48 hours at room temperature, while

  Aging the second plate for 48 hours in an oven at 60 C. The two plates are then heated to a temperature of 5 C by means of a cooling bath.

  The plates are then placed upside down on a four point support, and then a steel ball (500 g, 50 mm diameter) is dropped ten times.

  height of 50 cm on the back of each plate. The number of balls falling from the asphalt is recorded each time and the number of balls remaining in the asphalt on the plate.

  The number of balls falling each time is multiplied by a factor ranging from 10 to 1, from the first to the tenth drop of the 500 g ball. The sum of these factors is subtracted from 1000 to obtain a measure of the cohesive strength of the asphalt. The results are shown in Table III.

T A B L E A U III

  Latex Polyacrylic acid salt Initial cohesion force Number of remaining beads Heat aging (cohesive force) Number of remaining beads Asphalt (unmodified) less than 500 955 0 less SBR at 23% styrene SBR at 23% styrene reinforced with 6 parts, per 100 parts of rubber, of high styrene resin Polychloroprene Latex "KA 8306"

0.3 0.4 0.3

931 277

o0 ru do Co -4 -to

Claims (11)

  A method for reducing the setting time of a cationic emulsion of bitumen, asphalt, coal tar and their mixture, characterized in that it comprises incorporating into said emulsion an effective amount of a solution of cationic emulsifier and a polymer selected from the group consisting of a polymer of acrylic acid, methacrylic acid, their mixture or their salts to obtain a workable emulsion taken in less than 40 minutes.   2. A process according to claim 1, characterized in that the polymer is a low molecular weight polymer having a molecular weight less than 100,000 and is used in an amount sufficient to have about 0.001 part by weight, on a dry basis, per 100 parts by weight, based on   of said cationic asphalt emulsion.   3. Process according to claim 2, characterized in that the low molecular weight polymer is added to said cationic asphalt emulsion in the form of a mixture comprising 0.1 to 2.0 parts by weight on a dry basis of said low molecular weight polymer and 100 parts by dry weight of a latex of a polymer selected from the group consisting of: (i) copolymers formed from about 20 to 60% by weight of a vinyl aromatic monomer; C8 to C12 which may not be substituted or substituted by C1-C4 alkyl or chlorine or bromine; and from about 80 to 40% by weight of a C4 to C6 conjugated diolefin; (ii) terpolymers of about 20 to 60% by weight of a C8 to C12 vinyl aromatic monomer which may not be substituted or substituted by a C1 to C4 alkyl radical or a chlorine or bromine; from about 80 to 40% by weight of a C4 to C6 conjugated diolefin; and from about 0.5 to 10% by weight of one or more polymers selected from the group consisting of a C3 to C6 ethylenically unsaturated carboxylic acid; C1-C4 alkyl or hydroxyalkyl esters of C3-C6 ethylenically unsaturated carboxylic acid; C3 to C6 ethylenically unsaturated aldehydes; amides of C3-C6 ethylenically unsaturated carboxylic acids, these amides may not be substituted or substituted on the nitrogen atom by up to two radicals selected from the group consisting of C1-C4 alkyl radicals; and C1-C4 hydroxyalkyl radicals; (iii) polymers of one or more C4-C6 conjugated diolefins which may not be substituted or substituted with a chlorine atom; (Iv) copolymers formed to about X by weight of a C3-C6 alkenyl nitrile; the remainder being a C4 to C6 conjugated diolefin (v) copolymers of about 90 to 75% by weight of one or more C 2 or C 3 olefins; and from about 10 to 25% by weight of at least one C3 or C4 ethylenically unsaturated carboxylic acid; and (vi) copolymers of from 1 to about% by weight of a C2 or C3 alpha-olefin; from about 99 to 50% by weight of a C2 to C8 alkenyl or hydroxyalkenyl ester of a C1 to C12 saturated carboxylic acid; and, if desired, from about 0.5 to 10% by weight of one or more monomers selected from the group consisting of: b C 3 -C 6 ethylenically unsaturated carboxylic acids; C3 to C6 ethylenically unsaturated aldehydes; C1-C4 alkyl and hydroxyalkyl esters of C3-C6 ethylenically unsaturated carboxylic acids; and amides of C3 to C6 ethylenically unsaturated carboxylic acids, which amides may not be substituted or may be substituted on the nitrogen atom by one or more radicals selected from the group consisting of alkyl radicals. or C1-C4 hydroxyalkyl.   4. Process according to claim 3, characterized in that the mixture of the low molecular weight polymer selected from the group comprising polymers of acrylic acid, methacrylic acid, their mixture or their salts and said latex is produced in the form of anionic latexes which are then made cationic by addition of a proportion of up to 10%, based on the weight of the total polymer, of a cationic emulsifier and adjustment   pH to a value of less than about 5.   5. A process according to claim 4, characterized in that the low molecular weight polymer is selected from homopolymers or copolymers of acrylic acid or methacrylic acid having a molecular weight of less than 60,000 and is used in a from about 0.001 to about 1.0 parts by weight per 100 parts by weight on a dry basis of said emulsion   asphalt, bitumen, tar or their mixture.   6. Process according to claim 5, characterized in that the latex is a polymerized latex   in cold emulsion comprising about 20 to 40% by weight of styrene and about 80 to 60% by weight of butadiene.   7. Composition, characterized in that it comprises: I 0 parts by weight on a dry basis of a cationic emulsion selected from the group consisting of emulsion of asphalt, bitumen, coal tar and their mixture; and   about 0.001 to about 1.0 parts by weight on a dry basis of a polymer selected from the group consisting of polymers of acrylic acid, methacrylic acid, their mixture or their salts.   The composition of claim 6 further comprising up to about 20 parts by weight on a dry basis of a cationic latex of a polymer selected from the group consisting of: (i) copolymers formed from about 15 to 60% by weight of a C8 to C12 vinyl aromatic monomer which may not be substituted or substituted with a C1 to C4 alkyl radical or a chlorine or bromine atom; and from about 80 to 40% by weight of a C4 to C6 conjugated fine diol; (ii) terpolymers of from about 60% by weight of a C8-C12 vinyl aromatic monomer which may not be substituted or substituted by C1-C4 alkyl or chlorine or bromine ; from about 80 to 40% by weight of a C4 to C6 conjugated diolefin; and from about 0.5 to 10% by weight of one or more polymers selected from the group consisting of a C3-C6 ethylenically unsaturated carboxylic acid; C1-C4 alkyl or hydroxyalkyl esters of C3-C6 ethylenically unsaturated carboxylic acid; C3 to C6 ethylenically unsaturated aldehydes; C3-C6 ethylenically unsaturated carboxylic acid amides, which amides may be unsubstituted or substituted on the nitrogen atom by up to two radicals selected from the group consisting of C 1 -C 4 alkyl radicals and C1-C4 hydroxyalkyl radicals; (iii) polymers of one or more C4-C6 conjugated diolefins which may not be substituted or substituted with a chlorine atom; (iv) copolymers formed to about 40% by weight of a C3-C6 alkenyl nitrile; the remainder being a C4 to C6 conjugated olefin; and (v) copolymers of about 90 to 75% by weight of one or more C 2 or C 3 olefins; and   from about 10 to 25% by weight of at least one C3 or C4 ethylenically unsaturated carboxylic acid.   9. A composition according to claim 7, characterized in that the acrylic acid, methacrylic acid polymer, a mixture of both and   their salts have a molecular weight of less than 60,000.   10. A composition according to claim 8 characterized in that the latex is a cold emulsion polymer latex comprising about 20 to 40% by weight of styrene and about 80 to 60% by weight of butadiene. 11. A composition according to claim 9, further characterized in that it comprises up to about 1000 parts by weight of an aggregate per parts by weight on a dry basis of bitumen, asphalt, tar or their mixture.